1. Field of the Invention
The present invention relates generally to a plastic mold decapsuling apparatus, and more specifically to an apparatus which can dissolve a joint surface of a plastic mold or resin capsuled device such as semiconductor chip, capacitor, hybrid integrated circuit, etc. in order to inspect causes of defectiveness of the device.
2. Description of the Prior Art
To decapsule a plastic mold device by use of an etchant, coventionally; (A) etchant is taken from an etchant bottle through a pipette by an inspector and then put into a small recess formed in the plastic mold device; (B) etchant is transferred from an etchant bottle to a beaker, and then a plastic mold device is dipped into the etchant within the beaker; and (C) etchant is transferred from an etchant bottle to a special etchant reservoir and then sucked to the plastic mold device through a pipe provided for a decapsuling apparatus.
In these prior-art decapsuling methods, however, since etchant such as fuming nitric acid or concentrated sulfuric acid is transferred from an etchant bottle to another vessel, there exists a problem in that corrosive or irritant gas is produced and therefore the environment is contaminated.
When concentrated sulfuric acid is used as etchant, it is necessary to heat the etchant to about 290.degree. C. by a heating tank disposed between an etchant storage tank and a decapsuling plastic mold holder. As the method of heating an etchant by the heating tank, two methods can be considered. That is, a quantity of etchant used for one mold device is heated or a quantity of etchant used for several mold devices is heated at a time. In the former method, an addition of etchant heating time and etchant feeding time is required. On the other hand, in the latter method, a long time is required to heat the etchant at a time. In both cases, when several mold devices are to be decapsulated, there exists a problem in that it takes a relatively long etchant heating time. Further, since the etchant is a dangerous liquid, it is not preferable to heat a large quantity of etchant within the heat tank at a time.
When concentrated sulfuric acid is used as etchant, since the reactive force against the plastic mold device is strong, only a pressure reduction pump is usable, and the etchant is jetted to the decapsuling portion of the plastic mold device.
On the other hand, when fuming nitric acid is used as etchant, since the reactive force against the plastic mold device is mild, there exists a problem in that the pressure reduction pump is not usable because a large quantity of nitric acid is required. Further, it is necessary to circulate the etchant so as to be firmly applied to the decapsuling portion of the plastic mold device.
As the prior-art plastic mold decapsuling apparatus, U.S. Pat. No. 4,344,809 by Wensink, entitled JET ETCH APPARATUS FOR DECAPSULATION OF MOLDED DEVICES is incorporated herein by reference.